Best Impact Wrench
An impact wrench is the epitome of fastening power. When the hand ratchet falls short and even the breaker bar doesn't quite cut it, this tool steps up and breaks those fasteners free with ease and speed unlike anything else. This is why the impact wrench might be the most important tool a pit crew works with. What else could remove and replace lug-nuts so quickly while guaranteeing a racetrack ready job?
When buying an impact wrench you first need to consider your power source. Air driven impact wrenches offer the greatest power, but compressors are expensive and take up a lot of space. Corded electric impact wrenches are great for shop use and still offer some serious power without having to worry about compressors and air filters, but can't quite reach the peak output of air systems. Lastly, cordless impact wrenches offer unmatched versatility and portability, but you have to think about battery life and many are not strong enough for their intended jobs.
The other big factor to consider is the power your job requires. There are some impact wrenches on the market that can snap a steel bolt cleanly if you're not careful and something like that will be overkill for everything except ancient, rusted lug-nuts. Bigger isn't always better and you need to get the right tool for your job or risk breaking a part of your project.
Lastly, is it a comfortable tool to use? I'm not just talking about the weight and balance, but those are important factors. The nature of an impact wrench lends itself to vibration that can really wear on your wrists and arms over time. On top of that, wrenching your wrists when a fastener catches is all too common a problem. A good impact wrench should absorb a lot of the vibration before it reaches your hands and direct its power onto the fastener rather than you.
Best Air Impact Wrench:
Air impact wrenches are the original mechanics power tool, providing ample power for busting loose stubborn nuts and bolts that may have frozen in place over the years. Running off of compressed air, there is no risk of sparks from the motor or an extension cord being cut. This makes these tools considerably safer than their electric cousins. They are also more powerful, as an air motor can squeeze more power into a given space than an electric motor can.
Of course, to use them requires having an air compressor, and a pretty good one at that. Typically, the air consumption of these wrenches is about 5.2 CFM (cubic feet per minute). That's more than a small air compressor will put out. Generally speaking, you have to have an air compressor with at least a 2.5 HP motor and a 10 gallon tank to provide that much air. If you don't have that big a compressor, you'll spend all your time waiting for the compressor to recharge, so that you can use it.
Running an air impact wrench on less air than it needs will cause the power output to be lowered, as well as the speed. So, you will lose a lot of the advantage to using an air impact wrench in that case. It's better to buy a larger air compressor, so that it will provide sufficient air to the tool.
As an air tool, air impact wrenches need to be oiled daily. That means putting a couple of drops of air tool oil in the air inlet, before connecting it to the hose. This is about the only maintenance these tools need. Failure to oil it regularly will result in the vanes of the air motor inside the tool wearing, eventually lowering the amount of power the tool has.
The key to an air impact wrench is power. These tools are designed to provide a lot of power in a small package. That's what makes them so valuable. In addition to the raw horsepower of turning torque that the tool provides, these tools have a "hammer" inside the tool. On every revolution, the hammer strikes a metal anvil, providing a jolt to the fastener. It is these jolts, more than the torque of the wrench, which breaks stuck fasteners free. So, in addition to the horsepower of torque that the tool provides, the number of impacts per minute (IPM) that it can provide is important.
These tools are treated roughly in use, so the ruggedness of the tool is important. A poorly made tool will break under use, whereas one that is well made will be rugged enough to last for years of service.
The other important area is operator comfort. The vibration of the tool, along with the torque it provides, can be hard on the hands and wrists of the operator. Good tools will provide the operator with comfort and control, reducing operator fatigue.
I've limited this list to 1/2" drive impact wrenches, as that is the most common size used. Many of these models are available from their manufacturers in versions that are either larger or smaller than the ones selected as well.
The compact design of this impact wrench make it ideal for many projects, even though it isn't the most powerful wrench around. Even so, it provides an imparessive 450 ft. lbs. of torque in a lightweight 2.86 pound tool. Read Full Review
Snap-on tools are loved by mechanics everywhere. This magnesium-cased impact wrench is one of the most powerful around, providing 1190 ft. lbs. of breakaway power to get loose the most stubborn fasteners. Read Full Review
Ingersoll Rand brags about this tool having the best power-to-weight ratio of any impact wrench around. I can believe it, as it offers 1100 ft. lbs. of breakaway power, with a tool weight of only 3.95 pounds. Read Full Review
This impact wrench from Chicago Pneumatic is unique in that it is torque limited on assembly, while providing lots of torque for taking things apart. That solves the biggest problem that exists with impact wrenches, that of over-torquing fasteners when putting things back together again. Read Full Review
Best Cordless Impact Wrench:
All impact wrenches are designed for brute power. While they are used for assembly as well, the main idea behind their design is to make it possible to remove stuck nuts and bolts. The high-speed repeating impact provides the motive power to vibrate the fastener loose, providing multiple blows in the direction needed to loosen it.
This has caused a problem for cordless tools in the past. Until recent times, the batteries and motors of cordless tools just didn't have enough power to accomplish the goal of an impact wrench. But with the higher charge capacity of Lithium-Ion batteries, along with their higher voltage, designers have been able to produce motors for these tools which provide enough power to get the job done.
Still, these tools don't quite meet the specifications of pneumatic impact wrenches. On the flip side of the coin, they provide a lot more convenience, as you don't need to dig out a compressor and run a hose. If you're trying to work out in the field, it also saves you from the need for a generator to power your compressor (unless, of course, you have a gas driven generator). So in many cases, a cordless impact wrench might be a better choice than a pneumatic impact wrench.
One thing you have to have is a large capacity battery. "Slim-pack" or "fast-pack" batteries may not provide enough power to get you through a lot of fasteners. You're much better off with the extra capacity of the "fat-pack" batteries, even if they are heavier.
It can be a bit confusing comparing these to impact drivers. Both operate under the same principle, that of providing a rotary hammering action to move stubborn fasteners. However, the impact driver is designed for driving screws into difficult materials, such as pressure-treated lumber, where as a impact wrench is designed for removing hardware. Impact drivers will be rated in inch-pounds, where impact wrenches are rated in foot-pounds. One foot-pound is equal to 12 inch pounds of force.
Some of these impact wrenches use the same battery systems that are used for construction power tools. So, if you already have Milwaukee or Makita power tools, you will probably already have the batteries and chargers you need to operate these tools as well. That can save you a lot of money, as most manufacturers now provide their cordless tools as a "bare tool" without batteries and charger.
I've stuck with 1/2" drive impact wrenches for this list. Many of these companies also offer similar models in 3/8", 1/4" and even 3/4" drive models. But 1/2" drive is the most popular size impact wrench on the market.
DeWalt takes the day with the most powerful cordless impact on the market. This tool provides 1,200 ft. lbs. of breakaway torque to get even the stubborn ones loose. Its short length, at 8-13/16' makes it possible to get the tool into tight spaces. Read Full Review
Amongst Milwaukee's extensive selection of impact wrenches I found this one. Not only does it supply 1,100 ft. lbs. of nut busting torque, but the friction ring on the anvil makes changing out tools quick and easy. Read Full Review
Matco designed this tool for professional mechanics. That tells you that it's rugged and powerful. The all metal drive train ensures this tool isn't going to break down on you at a critical moment. Read Full Review
Snap-On is another company that offers an extensive lineup of cordless impact wrenches. I selected this one as my favorite, even though they have some newer models. Like all of Snap-On's tools, it’s built durable to last a long time. Read Full Review
Like usual, Makita pays attention to the details. The handle on this tool is designed to be shock absorbent. That makes it easier on your wrists, as well as helping to ensure longer tool life. Read Full Review
Best Electric Impact Wrench:
Corded impact wrenches may seem a bit of a contradiction, especially to those who are accustomed to using pneumatic tools. But for the guy who doesn't have an air compressor in his shop, they are a nice compromise. While not as powerful as a pneumatic impact, a corded impact wrench provides a considerable amount of power for changing tires or pulling an engine.
The one major drawback to a corded impact wrench is the size. Because electric motors are larger than their pneumatic equivalent, electric tools tend to be larger than comparable pneumatic ones. That same problem exists with impact wrenches, just as it does with any tool. So, you may not be able to use these tools in tight spaces. But that doesn't mean they aren't worth having.
Electric impact wrenches also tend to be more expensive out of the box than pneumatic ones are. But that's not really a fair comparison. If you don't already have an air compressor in your home or shop, buying one just so you can use an impact wrench is a considerable expense. At least with a corded electric impact wrench, you don't have to worry about that expense.
Like their pneumatic cousins, these are fairly simple tools, designed for one thing and one thing only; removing stubborn nuts and bolts. Although lots of people use impact wrenches to tighten nuts and bolts as well, they really aren't designed for that. You have no way of accurately controlling the torque when using an impact wrench to tighten bolts. That could cause stress fractures or even more serious damage if you aren't careful. Better to use a torque wrench.
The way that these impacts work is that they have an elliptical rotary hammer attached to the motor. Every revolution (sometimes twice per revolution, depending on the design of the impact wrench) the "hammer" strikes the "anvil" increasing the amount of torque the wrench provides. It also helps to vibrate the fastener which helps loosen it.
Impact wrenches are a great help when dealing with over-tightened fasteners, rusted fasteners or fasteners which have been left too long without loosening. The impact drive helps overcome the friction and spring tension in the fastener, allowing it to remove those stubborn fasteners.
Like all impact wrenches, the key to these tools is power which is measured in two ways. The first is by ft.lbs. of torque they can provide and then with the number of impacts per minute they offer. A high impact rate can accomplish more than a high torque rate in some circumstances.
Other than the torque, the other thing to look at in these tools is operator comfort. Using an impact wrench for an extended period of time can be hard on the wrists. Padded handles and electric brakes ease some of that jarring impact to the wrists, reducing fatigue and chance of injury.
I have stuck with 1/2" drive tools for this list, although most of these manufacturers also provide impact wrenches that with anvils that range from 1/4" up to 3/4". However, 1/2" is the most common size and I wanted to make sure I was comparing apples with apples, not apples with oranges.
These tools should only be used with heavy-duty extension cords made with 12 gauge wires. Using them with smaller gauge extension cords will limit the amount of electrical power available to the tool, reducing its effectiveness and increasing the chances of the extension cord overheating and becoming damaged. In extreme cases, it can even cause an electrical fire.
DeWalt's corded impact wrench is made with ball bearings in the motor, helping to ensure longer life. It is that, more than anything else, which won it the top spot on our list. This tool can take a beating and the ball bearings will outlast sleeved bearings any time. Read Full Review
Kobalt builds a rugged tool, coming in at 350 ft.lbs. of torque. They also provide a five year hassle free warranty, making them a top pick in this category. A live wire indicator and coming equipped with seven sockets are nice additions. Read Full Review
This tool from Craftsman comes with a work light, the only impact wrench that I've found that has one. It's located at the base of the handle too, so that there is no shadow from the tool's anvil which is a nice touch. Other than that, the specs on this tool and the Kobalt are identical, making it hard to pick between the two. Read Full Review
At 6.0 pounds, this is the lightest impact wrench on our list. While the specs say it's not as powerful as the Craftsman or Kobalt, I'd still put it beside them any day. Milwaukee's tools have a reputation for more power than they are rated for. Read Full Review
This Makita is the only impact wrench on our list that has a variable speed trigger. Although it doesn't have as much raw power as the other picks, this one gives you a lot of control. It also draws less current, which could be very useful in remote locations. Read Full Review